Internal Fixation of Posterior Pelvic Ring Injuries Using Iliosacral Screws in the Dysmorphic Upper Sacrum

INTRODUCTION: The correct usage of preoperative and intraoperative imaging allows fixation of posterior pelvic ring injuries with safely positioned iliosacral screws in the setting of sacral dysmorphism. STEP 1: PREOPERATIVE PLANNING: Obtain CT reformats along the longitudinal axis of the sacrum to determine the orientation and diameter of the osseous corridor for selection of the ideal screw size, length, and trajectory. STEP 2: PATIENT POSITIONING: Proper positioning enables reduction and accurate iliosacral screw placement. STEP 3: FRACTURE REDUCTION: Reduction of the posterior pelvic ring confers stability; if closed reduction is unsuccessful, proceed with open reduction. STEP 4: IDENTIFICATION OF THE ENTRY POINT: The entry point for an iliosacral screw into the upper sacral segment of a dysmorphic pelvis lies more posterior and caudal on the outer table of the posterior ilium than does a transsacral screw; adjust the entry point on the basis of inlet and outlet fluoroscopic views. STEP 5: DRILLING TECHNIQUE: Insert a stout cannulated drill bit of 4.5 to 5 mm (depending on the core diameter of the intended iliosacral screw) over the Kirschner wire and drill it into the sacral body under fluoroscopic guidance, in accordance with the preoperative plan. STEP 6: SCREW INSERTION: With the guidewire in the ideal position, measure the screw length off the inserted guidewire and advance a tap into the pathway; insert the screw and verify its position on the inlet, outlet, and lateral sacral views. RESULTS: Understanding the three-dimensional anatomy of the posterior pelvic ring is essential to successful reduction and fixation of unstable pelvic injuries with use of percutaneous iliosacral screws. Indications Contraindications Pitfalls & Challenges